// Adapted from https://gitlab.ilmiont.net/ilmiont/noisejs/. See NOTICE for licensing details.

/**
 * Perlin fade function.
 *
 * @param {Number} t
 * @return {Number}
 */
function fade(t) {
  return t * t * t * (t * (t * 6 - 15) + 10)
}

/**
 * Perlin lerp function.
 *
 * @param {Number} a
 * @param {Number} b
 * @param {Number} t
 * @return {Number}
 */
function lerp(a, b, t) {
  return (1 - t) * a + t * b
}

/**
 * Grad class.
 *
 * @package noisejs
 */
class Grad {
  /**
   * Constructor.
   *
   * @param {Number} x
   * @param {Number} y
   * @param {Number} z
   * @return {self}
   */
  constructor(x, y, z) {
    /**
     * x
     *
     * @type {Number}
     */
    this.x = x

    /**
     * y
     *
     * @type {Number}
     */
    this.y = y

    /**
     * z
     *
     * @type {Number}
     */
    this.z = z
  }

  /**
   * 2D dot product.
   *
   * @param {Number} x
   * @param {Number} y
   * @return {Number}
   */
  dot2(x, y) {
    return this.x * x + this.y * y
  }

  /**
   * 3D dot product.
   *
   * @param {Number} x
   * @param {Number} y
   * @param {Number} z
   * @return {Number}
   */
  dot3(x, y, z) {
    return this.x * x + this.y * y + this.z * z
  }
}

/**
 * noisejs
 *
 * @package noisejs
 */
class noise {
  /**
   * Constructor.
   *
   * @return {self}
   */
  constructor() {
    // Seed
    this.seed(0)
  }

  /**
   * Seed the noise generation.
   *
   * Supports 2^16 different seeding values.
   *
   * @param {Number} seed
   * @return {void}
   */
  seed(seed) {
    // Scale the seed
    if (seed > 0 && seed < 1) {
      seed *= 65536
    }

    // Floor the seed
    seed = Math.floor(seed)
    if (seed < 256) {
      seed |= seed << 8
    }

    // Iterate the seed
    for (var i = 0; i < 256; i++) {
      var v
      if (i & 1) v = p[i] ^ (seed & 255)
      else v = p[i] ^ ((seed >> 8) & 255)

      // Use permutation table
      perm[i] = perm[i + 256] = v
      gradP[i] = gradP[i + 256] = grad3[v % 12]
    }
  }

  /**
   * Generate 2D Simplex noise.
   *
   * @param {Number} xin
   * @param {Number} yin
   * @return {Number}
   */
  simplex2(xin, yin) {
    // Noise contributions from the three corners
    var n0, n1, n2

    // Skew the input space to determine which simplex cell we're in
    var s = (xin + yin) * F2
    var i = Math.floor(xin + s)
    var j = Math.floor(yin + s)
    var t = (i + j) * G2

    // The x,y distances from the cell origin, unskewed.
    var x0 = xin - i + t
    var y0 = yin - j + t

    // For the 2D case, the simplex shape is an equilateral triangle.
    // Determine which simplex we are in.
    // Offsets for second (middle) corner of simplex in (i,j) coords
    var i1, j1

    // lower triangle, XY order: (0,0)->(1,0)->(1,1)
    if (x0 > y0) {
      i1 = 1
      j1 = 0
    }
    // upper triangle, YX order: (0,0)->(0,1)->(1,1)
    else {
      i1 = 0
      j1 = 1
    }

    // A step of (1,0) in (i,j) means a step of (1-c,-c) in (x,y), and
    // a step of (0,1) in (i,j) means a step of (-c,1-c) in (x,y), where
    // c = (3-sqrt(3))/6
    var x1 = x0 - i1 + G2 // Offsets for middle corner in (x,y) unskewed coords
    var y1 = y0 - j1 + G2
    var x2 = x0 - 1 + 2 * G2 // Offsets for last corner in (x,y) unskewed coords
    var y2 = y0 - 1 + 2 * G2

    // Work out the hashed gradient indices of the three simplex corners
    i &= 255
    j &= 255

    // Get indices from permutation table
    var gi0 = gradP[i + perm[j]]
    var gi1 = gradP[i + i1 + perm[j + j1]]
    var gi2 = gradP[i + 1 + perm[j + 1]]

    // Calculate the contribution from the three corners
    var t0 = 0.5 - x0 * x0 - y0 * y0
    if (t0 < 0) {
      n0 = 0
    }
    // (x,y) of grad3 used for 2D gradient
    else {
      t0 *= t0
      n0 = t0 * t0 * gi0.dot2(x0, y0)
    }

    // Second corner
    var t1 = 0.5 - x1 * x1 - y1 * y1
    if (t1 < 0) {
      n1 = 0
    } else {
      t1 *= t1
      n1 = t1 * t1 * gi1.dot2(x1, y1)
    }

    // Third corner
    var t2 = 0.5 - x2 * x2 - y2 * y2
    if (t2 < 0) {
      n2 = 0
    } else {
      t2 *= t2
      n2 = t2 * t2 * gi2.dot2(x2, y2)
    }

    // Add contributions from each corner to get the final noise value.
    // The result is scaled to return values in the interval [-1,1].
    return 70 * (n0 + n1 + n2)
  }

  /**
   * Generate 3D Simplex noise.
   *
   * @param {Number} xin
   * @param {Number} yin
   * @param {Number} zin
   * @return {Number}
   */
  simplex3(xin, yin, zin) {
    // Noise contributions from the four corners
    var n0, n1, n2, n3

    // Skew the input space to determine which simplex cell we're in
    var s = (xin + yin + zin) * F3
    var i = Math.floor(xin + s)
    var j = Math.floor(yin + s)
    var k = Math.floor(zin + s)

    // The x,y distances from the cell origin, unskewed.
    var t = (i + j + k) * G3
    var x0 = xin - i + t
    var y0 = yin - j + t
    var z0 = zin - k + t

    // For the 3D case, the simplex shape is a slightly irregular tetrahedron.
    // Determine which simplex we are in.
    // Offsets for second corner of simplex in (i,j,k) coords
    // Offsets for third corner of simplex in (i,j,k) coords
    var i1, j1, k1
    var i2, j2, k2
    if (x0 >= y0) {
      if (y0 >= z0) {
        i1 = 1
        i2 = 1
        j1 = 0
        j2 = 1
        k1 = 0
        k2 = 0
      } else if (x0 >= z0) {
        i1 = 1
        i2 = 1
        j1 = 0
        j2 = 0
        k1 = 0
        k2 = 1
      } else {
        i1 = 0
        i2 = 1
        j1 = 0
        j2 = 0
        k1 = 1
        k2 = 1
      }
    } else {
      if (y0 < z0) {
        i1 = 0
        i2 = 0
        j1 = 0
        j2 = 1
        k1 = 1
        k2 = 1
      } else if (x0 < z0) {
        i1 = 0
        i2 = 0
        j1 = 1
        j2 = 1
        k1 = 0
        k2 = 1
      } else {
        i1 = 0
        i2 = 1
        j1 = 1
        j2 = 1
        k1 = 0
        k2 = 0
      }
    }

    // A step of (1,0,0) in (i,j,k) means a step of (1-c,-c,-c) in (x,y,z),
    // a step of (0,1,0) in (i,j,k) means a step of (-c,1-c,-c) in (x,y,z), and
    // a step of (0,0,1) in (i,j,k) means a step of (-c,-c,1-c) in (x,y,z), where
    // c = 1/6.

    // Offsets for second corner
    var x1 = x0 - i1 + G3
    var y1 = y0 - j1 + G3
    var z1 = z0 - k1 + G3

    // Offsets for third corner
    var x2 = x0 - i2 + 2 * G3
    var y2 = y0 - j2 + 2 * G3
    var z2 = z0 - k2 + 2 * G3

    // Offsets for fourth corner
    var x3 = x0 - 1 + 3 * G3
    var y3 = y0 - 1 + 3 * G3
    var z3 = z0 - 1 + 3 * G3

    // Work out the hashed gradient indices of the four simplex corners
    i &= 255
    j &= 255
    k &= 255

    //Get indices from permutation table
    var gi0 = gradP[i + perm[j + perm[k]]]
    var gi1 = gradP[i + i1 + perm[j + j1 + perm[k + k1]]]
    var gi2 = gradP[i + i2 + perm[j + j2 + perm[k + k2]]]
    var gi3 = gradP[i + 1 + perm[j + 1 + perm[k + 1]]]

    // Calculate the contribution from the four corners
    // First corner
    var t0 = 0.6 - x0 * x0 - y0 * y0 - z0 * z0
    if (t0 < 0) {
      n0 = 0
    }
    // (x,y) of grad3 used for 2D gradient
    else {
      t0 *= t0
      n0 = t0 * t0 * gi0.dot3(x0, y0, z0)
    }

    // Second corner
    var t1 = 0.6 - x1 * x1 - y1 * y1 - z1 * z1
    if (t1 < 0) {
      n1 = 0
    } else {
      t1 *= t1
      n1 = t1 * t1 * gi1.dot3(x1, y1, z1)
    }

    // Third corner
    var t2 = 0.6 - x2 * x2 - y2 * y2 - z2 * z2
    if (t2 < 0) {
      n2 = 0
    } else {
      t2 *= t2
      n2 = t2 * t2 * gi2.dot3(x2, y2, z2)
    }

    // Fourth corner
    var t3 = 0.6 - x3 * x3 - y3 * y3 - z3 * z3
    if (t3 < 0) {
      n3 = 0
    } else {
      t3 *= t3
      n3 = t3 * t3 * gi3.dot3(x3, y3, z3)
    }

    // Add contributions from each corner to get the final noise value.
    // The result is scaled to return values in the interval [-1,1].
    return 32 * (n0 + n1 + n2 + n3)
  }

  /**
   * Generate 2D Perlin noise.
   *
   * @param {Number} x
   * @param {Number} y
   * @return {Number}
   */
  perlin2(x, y) {
    // Find unit grid cell containing point
    var X = Math.floor(x),
      Y = Math.floor(y)

    // Get relative xy coordinates of point within that cell
    x = x - X
    y = y - Y

    // Wrap the integer cells at 255 (smaller integer period can be introduced here)
    X = X & 255
    Y = Y & 255

    // Calculate noise contributions from each of the four corners
    var n00 = gradP[X + perm[Y]].dot2(x, y)
    var n01 = gradP[X + perm[Y + 1]].dot2(x, y - 1)
    var n10 = gradP[X + 1 + perm[Y]].dot2(x - 1, y)
    var n11 = gradP[X + 1 + perm[Y + 1]].dot2(x - 1, y - 1)

    // Compute the fade curve value for x
    var u = fade(x)

    // Interpolate the four results
    return lerp(lerp(n00, n10, u), lerp(n01, n11, u), fade(y))
  }

  /**
   * Generate 3D Perlin noise.
   *
   * @param {Number} x
   * @param {Number} y
   * @param {Number} z
   * @return {Number}
   */
  perlin3(x, y, z) {
    // Find unit grid cell containing point
    var X = Math.floor(x),
      Y = Math.floor(y),
      Z = Math.floor(z)

    // Get relative xyz coordinates of point within that cell
    x = x - X
    y = y - Y
    z = z - Z

    // Wrap the integer cells at 255 (smaller integer period can be introduced here)
    X = X & 255
    Y = Y & 255
    Z = Z & 255

    // Calculate noise contributions from each of the eight corners
    var n000 = gradP[X + perm[Y + perm[Z]]].dot3(x, y, z)
    var n001 = gradP[X + perm[Y + perm[Z + 1]]].dot3(x, y, z - 1)
    var n010 = gradP[X + perm[Y + 1 + perm[Z]]].dot3(x, y - 1, z)
    var n011 = gradP[X + perm[Y + 1 + perm[Z + 1]]].dot3(x, y - 1, z - 1)
    var n100 = gradP[X + 1 + perm[Y + perm[Z]]].dot3(x - 1, y, z)
    var n101 = gradP[X + 1 + perm[Y + perm[Z + 1]]].dot3(x - 1, y, z - 1)
    var n110 = gradP[X + 1 + perm[Y + 1 + perm[Z]]].dot3(x - 1, y - 1, z)
    var n111 = gradP[X + 1 + perm[Y + 1 + perm[Z + 1]]].dot3(
      x - 1,
      y - 1,
      z - 1,
    )

    // Compute the fade curve value for x, y, z
    var u = fade(x)
    var v = fade(y)
    var w = fade(z)

    // Interpolate
    return lerp(
      lerp(lerp(n000, n100, u), lerp(n001, n101, u), w),
      lerp(lerp(n010, n110, u), lerp(n011, n111, u), w),
      v,
    )
  }
}

/**
 * 3D gradients
 *
 * @type {Array}
 */
var grad3 = [
  new Grad(1, 1, 0),
  new Grad(-1, 1, 0),
  new Grad(1, -1, 0),
  new Grad(-1, -1, 0),
  new Grad(1, 0, 1),
  new Grad(-1, 0, 1),
  new Grad(1, 0, -1),
  new Grad(-1, 0, -1),
  new Grad(0, 1, 1),
  new Grad(0, -1, 1),
  new Grad(0, 1, -1),
  new Grad(0, -1, -1),
]

/**
 * Permutation table
 *
 * @type {Array}
 */
var p = [
  151, 160, 137, 91, 90, 15, 131, 13, 201, 95, 96, 53, 194, 233, 7, 225, 140,
  36, 103, 30, 69, 142, 8, 99, 37, 240, 21, 10, 23, 190, 6, 148, 247, 20, 234,
  75, 0, 26, 197, 62, 94, 252, 219, 203, 117, 35, 11, 32, 57, 177, 33, 88, 237,
  149, 56, 87, 174, 20, 125, 136, 171, 168, 68, 175, 74, 165, 71, 134, 139, 48,
  27, 166, 77, 146, 158, 231, 83, 111, 229, 122, 60, 211, 133, 230, 220, 105,
  92, 41, 55, 46, 245, 40, 244, 102, 143, 54, 65, 25, 63, 161, 1, 216, 80, 73,
  209, 76, 132, 187, 208, 89, 18, 169, 200, 196, 135, 130, 116, 188, 159, 86,
  164, 100, 109, 198, 173, 186, 3, 64, 52, 217, 226, 250, 124, 123, 5, 202, 38,
  147, 118, 126, 255, 82, 85, 212, 207, 206, 59, 227, 47, 16, 58, 17, 182, 189,
  28, 42, 223, 183, 170, 213, 119, 248, 152, 2, 44, 154, 163, 70, 221, 153, 101,
  155, 167, 43, 172, 9, 129, 22, 39, 253, 19, 98, 108, 110, 79, 113, 224, 232,
  178, 185, 112, 104, 218, 246, 97, 228, 251, 34, 242, 193, 238, 210, 144, 12,
  191, 179, 162, 241, 81, 51, 145, 235, 249, 14, 239, 107, 49, 192, 214, 31,
  181, 199, 106, 157, 184, 84, 204, 176, 115, 121, 50, 45, 127, 4, 150, 254,
  138, 236, 205, 93, 222, 114, 67, 29, 24, 72, 243, 141, 128, 195, 78, 66, 215,
  61, 156, 180,
]

// Double the permutation table length (avoid array wrapping)
var perm = new Array(512)
var gradP = new Array(512)

// Skewing and unskewing factors for generating 2D, 3D and 4D noise
var F3 = 1 / 3
var G3 = 1 / 6
var F2 = 0.5 * (Math.sqrt(3) - 1)
var G2 = (3 - Math.sqrt(3)) / 6

const noisejs = new noise()
export default noisejs
